A medical marijuana grower whose farms were raided in October 2011 has been sentenced to 15 years in federal prison.

Senior U.S. District Judge Owen M. Panner sentenced Brian Wayne Simmons, 40, of Medford, today on charges of conspiracy and manufacturing and distributing marijuana. Simmons was convicted in a four-day trial in December 2012.

Simmons owned and operated Brian's Green Thumb Farm on East Gregory Road in Central Point. U.S. Drug Enforcement Administration agents and local police raided Simmons' farm in October 2011, seizing 456 large marijuana plants. Agents seized an additional 64 large marijuana plants at a second grow site on Dark Hollow Road, near Medford.

The plants were 5 to 8 feet tall, each capable of producing upwards of 10 pounds of marijuana per plant, court records show. Agents also seized thousands of pounds of harvested marijuana being processed at the two sites.

Prosecutors said Simmons had registered more than 20 people as growers on his sites in an effort to make it look like he was complying with the Oregon Medical Marijuana Act. At trial, one of those registered growers testified that she didn't know the patients or tend the plants herself.

The investigation revealed that Simmons had been growing and selling marijuana since at least 2009, with documented sales of more than $740,000 for the 2009 and 2010 grow seasons. Based on the seized evidence, Simmons had roughly quadrupled the size of his operation by 2011, officials said.

A co-defendant, Michael Grantski, was accused of overseeing the Dark Hollow Road site, but was acquitted in December. Another co-defendant, Michael Peru, pleaded guilty and cooperated with federal investigators. He is awaiting sentencing.

In a statement released today, U.S. Attorney Amanda S. Marshall said Simmons' case "represents another gross abuse of the Oregon Medical Marijuana Program." She said her office will continue to indict people who violate state and federal law by producing and selling large quantities of marijuana for profit, and will seize assets used in such activity.